Download Chloride - Ozarks Environmental and Water Resources Institute

Standard Operating Procedure for:
accumet excel XL25 Dual Channel pH/Ion Meter
for Chloride Concentration Determination
(Chloride_R02.doc)
Missouri State University
and
Ozarks Environmental and Water
Resources Institute (OEWRI)
Prepared by: __________________________________
OEWRI Quality Assurance Coordinator
Date: _____________
Approved by: __________________________________
OEWRI Director
Date: _____________
ID: Chloride
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Table of Contents
1
Identification of the test method ................................................................................. 3
2
Applicable matrix or matrices...................................................................................... 3
3
Detection limit............................................................................................................... 3
4
Scope of the test method ............................................................................................. 3
5
Summary of test method.............................................................................................. 3
6
Definitions ..................................................................................................................... 3
7
Interferences ................................................................................................................. 4
8
Health and safety .......................................................................................................... 4
9
Personnel qualifications .............................................................................................. 4
10
Equipment and supplies .............................................................................................. 5
11
Reagents and standards .............................................................................................. 5
12
Sample collection, preservation, shipment and storage ........................................... 5
13
Quality control .............................................................................................................. 5
14
Calibration and standardization .................................................................................. 7
15
Sample Analysis ........................................................................................................... 8
16
Data acquisition, calculations, and reporting ............................................................. 9
17
Computer hardware and software ..............................................................................10
18
Method performance ...................................................................................................10
19
Pollution prevention ....................................................................................................10
20
Data assessment and acceptable criteria for quality control measures..................10
21
Corrective actions for out-of-control or unacceptable data .....................................10
22
Waste management .....................................................................................................11
23
References ...................................................................................................................11
24
Tables, diagrams, flowcharts and validation data .....................................................11
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1
Identification of the test method
Operation of the accumet excel XL25 dual channel pH/Ion meter
for chloride concentration determination.
2
Applicable matrix or matrices
This method is suitable for the determination of chloride concentrations in
potable, surface, and waste waters. The accument excel XL25 meter has an operating
range of 1 x 10-5 to 100 ppm chloride.
3
Detection limit
The practical detection limit is 0.1 ppm.
4
Scope of the test method
This standard operating procedure provides Missouri State University (MSU)
laboratory personnel protocol for determining chloride concentration in water samples.
5
Summary of test method
A water sample is combined with an ion strength adjuster to create a uniform
background ionic strength, which provides more accurate and reproducible
measurements with the ion selective electrode (ISE) used for these determinations. The
chloride electrode is introduced to the sample and the electrode’s sensing membrane
develops an electrical potential which is proportional to the activity of the chloride anion
in the sample. The sample activity is compared to the activity of the range of standards
used to calibrate the instrument and chloride concentration is calculated.
6
Definitions
6.1
Analytical batch: The set of samples processed at the same time.
6.2
Calibration standard: A solution prepared from the primary dilution standard
solution or stock standard solutions. The calibration standards are used to
calibrate the instrument response with respect to analyte concentration.
6.3
Chain of Custody (COC): Used to describe the written record of the collection
possession and handling of samples. Chain of custody forms should be
completed as described in the Chain of Custody SOP # 1030R01. Chain of
custody (COC) forms are located on a board in Temple Hall 125.
6.4
Field Duplicate (FD): Two samples taken at the same time and place under
identical circumstances and which are treated identically throughout field and
laboratory procedures. Analysis of field duplicates indicates the precision
associated with sample collection, preservation, and storage, as well as
laboratory procedures.
6.5
Ionic Strength Adjuster (ISA): Buffer solution added to the samples and
standards to create a uniform background ionic strength for increased accuracy
and precision.
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6.6
Laboratory Duplicate (LD): Two aliquots of the same environmental sample
treated identically throughout a laboratory analytical procedure. Analysis of
laboratory duplicates indicates precision associated with laboratory procedures
but not with sample collection, preservation, or storage procedures.
6.7
Laboratory Reagent Blank (LRB): An aliquot of HPLC water that is used to
calibrate the instrument at the beginning of the analysis and is analyzed within
the batch analysis sequence to determine if analytes or interferences are present
in the laboratory environment or the apparatus.
6.8
Method detection limit (MDL): The lowest level at which an analyte can be
detected with 99 percent confidence that the analyte concentration is greater
than zero. To calculate the MDL:
a.
Analyze seven aliquots of HPLC water including all sample processing
steps prior to the determination.
b.
Calculate the standard deviation (s).
c.
The multiplier used to derive the MDL is from a table of a one-sided t
distribution where the value of t for 7 – 1 = 6 degrees of freedom at the
99% level was selected. This value is 3.14.
d.
The product 3.14 times s is the desired MDL.
6.9
Relative Percent Difference (RPD): calculated as the difference between a
sample and duplicate results, divided by the average of the sample and duplicate
results, multiplied by 100%.
6.10
Standard Check: Standards analyzed as samples to monitor instrument shift or
analyst error.
7
Interferences
Cyanide, thiosulfate, and ammonia are potential interferences to the chloride
electrode and could significantly influence electrode response. Samples should be free
of sulfide as it destroys the electrode surface. Wastewater samples should be screened
for sulfide and ammonia content prior to being exposed to the electrode associated with
this meter.
8
Health and safety
This analysis involves handling freshwater samples that may contain live
microorganisms and therefore pose some threat of infection. Laboratory personnel who
are routinely exposed to such water samples are encouraged to protect themselves from
water borne illnesses by wearing clean disposable gloves and washing their hands
frequently.
9
Personnel qualifications
Laboratory personnel shall have a working knowledge of this analytical
procedure and will have received training from an MSU employee knowledgeable of the
proper sample analysis procedures. Prior to the first batch of sample analyses, the
analyst will complete a demonstration of capability exercise as described below in the
Quality control section.
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10
11
12
13
Equipment and supplies
10.1 Fisher Accumet Excel XL 25 with Chloride ISE Electrode.
10.2
Fisher Scientific stir plate.
10.3
100 ml Griffin Beakers (Fisher Cat. No. S63242).
10.4
Stir bars (Fisher Cat. No. 14-513-58SIX).
10.5
1000 µL pipette and tips (Fisher Cat. No. 21-377-146).
10.6
10 µL pipette and tips.
Reagents and standards
11.1 Chloride Electrode Storage Solution: 98.4% H2O, 1% KHP, and 0.6% KCl (98.4
ml H2O, 1 g KHP, and 0.6 g KCl).
11.2
DI water: For rinsing electrode between samples.
11.3
Fisher Accumet Chloride ISE Electrode Filling Solution (Fisher Cat. No. 13-620432): Reference solution for electrode.
11.4
HPLC (Fisher Cat. No. W5-4): For mixing standards.
11.5
Spex CertiPrep Ion Chromatography Chloride Standard Solution – 100mg/l
(Fisher Cat. No. AS-CL9-1X).
11.6
Thermo Scientific Orion ISE Ionic Strength Adjuster (Fisher Cat. No. 13-641852): Use 2 ml/100 ml sample to produce a uniform background ionic strength.
Sample collection, preservation, shipment and storage
12.1 Refer to the Water Sampling SOP for appropriate collection procedures (SOP:
1040R01 Water Sampling.doc).
12.2
Samples are stored on ice for transport to the laboratory and are refrigerated
immediately upon transfer to the laboratory. Chloride samples do not require any
preservation solution addition.
12.3
There is a 28 day holding time for chloride (EPA-600/4-79-020), however,
samples should be analyzed as soon as possible.
Quality control
13.1 Quality control program: The minimum requirements of the quality control
program for this analysis consist of an initial demonstration of laboratory
capability, and the periodic analysis of laboratory reagent blanks and other
laboratory solutions as a continuing check on performance. The laboratory must
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maintain performance records that define the quality of the data that are
generated.
13.2
13.3
13.4
a.
Analyses of laboratory blanks are required to demonstrate freedom from
contamination. Analyze one LRB for every 10 samples analyzed.
b.
The laboratory shall, on an ongoing basis, demonstrate through
calibration verification and analysis of the ongoing precision sample that
the analysis system is in control. Each standard used to calibrate the
instrument is re-analyzed at the end of the batch or after every 20
samples and at the end of the batch to verify calibration and quantify
instrument drift. A laboratory duplicate is analyzed for every 10 samples
analyzed to quantify precision.
d.
The laboratory should maintain records to define the quality of data that is
generated.
Demonstration of capability; a new analyst should:
a.
Read this standard operating procedure,
b.
Demonstrate to a previously trained analyst that the procedures outlined
here are being followed, and
c.
Successfully report data collected using these procedures to the QA/QC
manager.
Initial demonstration of performance. The following must be satisfied before the
analytical procedure may be used for samples.
a.
Method Detection Limit (MDL): To establish the ability to detect the
analyte, the analyst shall determine the MDL by carrying through 7 or
more separately prepared reagent blank solutions through the analytical
procedure. The average value, X, and the standard deviation of the
values, s, shall be calculated. The MDL is equal to 3s (3 × standard
deviation). The MDL and average value, X, must both be less than 0.10
mg Cl/L.
b.
Initial Precision and Recovery: To establish the ability to generate
acceptably precise and accurate results, the operator shall perform 10
replicates of a mid-range standard. Using the results of the replicates,
compute the average value, X, and the standard deviation, s, for the
analyte. The value of X should be within ± 10% of the true value. The
standard deviation should be less than or equal to 10% of the average
value.
Duplicate reproducibility:
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a.
Measure the sample and a separate aliquot of the same sample (LD).
b.
The relative percent difference (RPD) between the two values should be
≤ 10% of their average value.
c.
Use equation 1 to calculate RPD:
d.
14
Equation 1:
RPD (%) = (A – B) x 100%
(A + B)/2
Where:
A = first measurement, and
B = duplicate measurement
Analyze one set of duplicates for every 10 samples analyzed.
Calibration and standardization
14.1 The accumet excel XL25 chloride meter will be calibrated prior to every batch
analysis.
14.2
Calibration employs a standard curve derived from plotting electrical potential or
the activity produced from the standard solutions (including the reagent blank)
versus known chloride anion concentration in the standards. The data is fit to a
linear equation using the software associate with the meter and concentration is
presented on the screen.
14.3
The chloride electrode will always be stored in the Chloride Electrode Storage
Solution: 98.4% HPLC H2O, 1% KHP, and 0.6% KCl (98.4 ml H2O, 1 g KHP, and
0.6 g KCl) or will be cleaned, drained, and stored within the original box when not
in use for extended periods of time.
14.4
Clean and perform routine maintenance as outlined in the accument excel XL25
operator’s manual.
14.5
Calibration Solutions Preparation
a.
Prepare the Blank (0.00ppm) by using a 40 ml aliquot of HPLC water
only.
b.
Prepare Standard 1 (10 ppm) by removing a 4 ml aliquot of Spex
CertiPrep 100 ppm Standard Stock Solution from the standard bottle with
a pipette and clean tip and combine it with 36 ml HPLC in a clean beaker.
c.
Prepare Standard 2 (50 ppm) by removing a 20 ml aliquot of Spex
CertiPrep 100 ppm Standard Stock Solution from the standard bottle with
a pipette and clean tip and combine it with 20 ml HPLC in a clean beaker.
d.
Prepare Standard 3 (100 ppm) by removing a 40 ml aliquot of Spex
CertiPrep 100 ppm Standard Stock Solution from the standard bottle with
a pipette and clean tip and transfer it to a clean beaker.
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e.
14.6
15
Remove 0.8 ml of the ionic strength adjuster solution from the bottle with
a pipette and clean tip and transfer it to each standard and the blank.
Calibration Procedures
a.
Add a clean stir bar to each standard and the blank.
b.
Rinse the electrode with HPLC water and blot with paper towel.
c.
Place the Blank on the stir plate and turn dial to 6.
d.
Immerse electrode into the blank solution but DO NOT allow the stir bar
to touch the electrode.
e.
Press Standardize on the Ion Measure screen to access the
standardization screen.
f.
Press Clear if necessary to remove a previous standardization.
g.
Proceed when the screen reads “Not standardized”.
h.
Press Blank. A beaker icon labeled blank will be displayed on the Ion
Measure screen.
i.
Remove the Blank from the stir plate, rinse the electrode, and blot with a
paper towel. Place Standard 1 on the stir plate, and immerse the
electrode in the standard.
j.
Press Standardize and then Standard. The screen will flash each
standard icon once and then a numeric keypad will appear. Input the
value of the standard and press Enter.
k.
The screen will illustrate the value of the standard solution in the flashing
beaker. Wait until Stable appears on the screen and press Confirm once
to confirm the standardization.
l.
Repeat procedures 14.6 i-k with Standard 2 and Standard 3.
Sample Analysis
15.1 Thoroughly shake sample in sample bottle and measure 40 ml into a clean
labeled beaker.
15.2
Remove 0.8 ml of the ionic strength adjuster solution from the solution bottle with
a pipette and clean tip and transfer it to the sample.
15.3
Add a clean stir bar to each sample.
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15.4
Rinse the electrode with HPLC and blot with paper towel.
15.5
Place the sample on the stir plate and turn dial to 6.
15.6
Immerse the electrode in the stirring sample but DO NOT allow the stir bar to
touch the electrode.
15.7
Press Measure to begin the analysis of the sample.
15.8
Wait until Stable appears on the screen, press Log Data, and record the
concentration on the chloride bench sheet.
15.9
Remove the electrode from the sample and rinse with HPLC water.
15.10 Repeat procedures 15.1-15.9 until all samples are analyzed.
15.11 Use a separate 40 ml aliquot of one of the samples to produce a Laboratory
Duplicates (LD) for every 10 samples analyzed. Record the sample number and
“-LD” on the bench sheet when recording the concentration of the laboratory
duplicate.
15.12 Use the original standards and blank to check the calibration and instrument drift
by analyzing each solution after every 20 samples and at the end of the batch.
Repeat procedures 15.1 – 15.9 for each standard and blank treating them as
“samples” so the original calibration is used throughout the analysis. Record
“Standard 1”, “Standard 2”, “Standard 3”, and “Blank” concentrations on the
bench sheet.
16
Data acquisition, calculations, and reporting
16.1 Data Exporting Procedures
a.
Press View in the mV setup screen.
b.
Press Export View and Header to save data in HTML format.
c.
Press SD Card and name the file using the alphanumeric keypad at the
bottom of the screen. The file name should include “Chloride Data”, the
date of analyses, the project names and date of sample collection
associated with the COCs completed during the analysis.
d.
Press OK in the upper right corner of the Save As screen.
e.
Close all applications prior to SD card removal.
f.
Press gently down on the card to unlock it and when the card disengages
and pops up, pull it from the expansion slot.
g.
Data can be viewed using Windows Explorer:
1.
Press Setup and then View.
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2.
17
16.2
The software associated with the meter calculates all concentrations base on the
initial batch calibration.
16.3
Reporting results: Results should be reported to the 0.1 mg Cl/L precision.
Computer hardware and software
17.1 Word: This document and attached bench sheet are prepared using Microsoft
Word.
17.2
18
21
The applicable range for the method is 0.1 to 100 mg Cl/L and may be extended
by dilution.
Pollution prevention
19.1 All wastes from these procedures shall be collected and disposed of according to
existing waste policies within the MSU Geography, Geology, and Planning
Department.
19.2
20
Excel: Quality control charts are created using Excel.
Method performance
18.1 The desired performance criteria for this measurement are:
a.
Detection limit: 0.1 mg Cl/L
b.
Precision: ± 10% RPD
c.
Accuracy: ± 10% RPD
d.
Minimum Quantification Interval: 0.1 mg Cl/L
18.2
19
Data is listed inversely of analysis sequence.
Volumes of reagents made should mirror the number of samples being analyzed.
These adjustments should be made to reduce waste.
Data assessment and acceptable criteria for quality control measures
20.1 The analyst should review all data for correctness.
20.2
Precision values are calculated for pairs of duplicate analyses. The desired
precision is ± 10% RPD.
20.3
Accuracy values are calculated for standard checks analyzed within and at the
end of the batch. The desired accuracy is ± 10% RPD.
20.4
The desired detection limit is 0.1 mg Cl/L.
20.5
All completed bench sheets are reviewed by the OEWRI QA/QC manager.
Corrective actions for out-of-control or unacceptable data
21.1 The results for precision, accuracy, and blank data are compared to acceptable
values for these analyses: ± 10% RPD and 0.1 mg Cl/L respectively.
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21.2
If a blank value exceeds 0.1 mgCl/L during batch analysis then the analyst
should immediately re-analyze the blank and if the blank continues to exceed the
MDL contact the QA/QC manager.
21.3
If data are unacceptable for any reason, the analyst should review their analytical
techniques prior to conducting these analyses again.
21.4
The batch may be re-analyzed as QA/QC dictates.
21.5
The meter may require trouble-shooting techniques if the data are unacceptable
beyond regular maintenance including cleaning the electrode, changing the
reference solution, or replacing the electrode. All maintenance and repairs must
be recorded in the instrument log book.
22
Waste management
The waste generated in this method are not hazardous. The quantities
generated are small and waste can be discarded in the laboratory sink.
23
References
23.1 Accumet Excel User Manual. 2004. Fisher Scientific.
24
Tables, diagrams, flowcharts and validation data
24.1 There are no tables, diagrams, or flowcharts for this method.
24.2
The following page contains the chloride bench sheet. The analyst should copy
this form and use one for each batch of samples analyzed.
Missouri State University
Ozarks Environmental and Water Resources Institute
Chloride Bench Sheet
Analyst: _____________________________
Data reviewed by:
Date analyzed: ______________________
Projects COCs associated with Analysis: ___________________________________________
Sample Data
Sample
Date Sample
Identification
Collected
Chloride
Concentration (mg/l)
Chloride
Concentration (mg/l)
Blank (0ppm)
Std. 1 (10ppm)
Std. 2 (50ppm)
Std. 3 (100ppm)
Comments: __________________________________________________________________
Chloride – Bench Procedures



Make/Label bench sheet
Set samples out to warm up to room temp
Make blank/standards for calibration
Blank (0ppm)
Std1 (10ppm)
Std2 (50ppm)
Std3 (100ppm)


H2O
40.0 mL
39.2 mL
36.0 mL
32.0 mL
IA
0.8 mL
0.8 mL
0.8 mL
0.8 mL
ClN/A
0.8 mL
4.0 mL
8.0 mL
Read blank/standards
o Standardize, clear, standardize, blank: wait-confirm
o Standardize, standard, enter #: wait-confirm
Samples
Samples




Sample
40.0 mL
IA
0.8 mL
Rinse between each probe reading
If any samples read ‘under range’ write that down
LD every ~12 samples
Run standards again after samples